Electrical operating device for neon and like signs



March 13, 1934. c. P. BOUCHER 1,950,394

ELECTRICAL OPERATING DEVICE FOR NEON AND LIKE SIGNS Filed Dec. 14, 19512% 37 35 23 3a lj EH m /2 as I "1 --E i E Ht-{I 4 Ezzgm FFCS I.

FFG. a: L05 [0 AQQ/ 1'67 8- w, \W W HVVE/VTQR C W V Patented Mar. 13,1934 PATENT OFFICE I ELECTRICAL OPERATING DEVICE FOR NEON AND LIKE SIGNSCharles Philippe Boueher, Montreal, Quebec,.

Canada,

assignor of one-half to Lindsay Carlton Mickles, Montreal, Quebec,

Canada.

Application December 14, 1931, Serial No. 580,793

9 Claims.

This invention relates to luminescent electric signs, such asneon'signsand more particularly to an electrical system and apparatusfor the operation of the same.

One of the objects of my invention is to provide a simple, inexpensive,and thoroughly practical system and apparatus for the highly efiicientand reliable operation of luminescent gaseous conduction devices orgas-filled tubes, such as neon tubes, of various shapes and sizescomprising, for example, an electric sign.

Another object is to maintain maximum clear and brilliant operation ofluminescent tubes or devices of the character indicated throughout longperiods of continuous and uninterrupted use at maximum operatingefiiciency, at minimum expense and with minimumdanger to life andproperty.

Another object is to assure uniform brilliancy of operation of variousluminescent gas-filled tubes forming part of the same luminescentdisplay, in spite of various inequalities and differences in the severaltubes in matters of size, shape, the nature and pressure of theluminiferous gas used and like physical differences which affect theelectrical characteristics of the tubes em- -ployed.

Other objects in part will be obvious and in part pointed outhereinafter.

The invention, accordingly, consists in the various combinations ofelements, features of construction and arrangement of parts as describedherein and shown in the accompanying drawing, and the scope of theapplication 'of which is indicated in the following claims.

Referring now to the drawing:

Figure 1 is a diagram of the electrical system and apparatus foroperating a plurality of individual luminescent gas filled tubescomprising a single luminescent sign or display, and Figure 2 is anenlarged view of a luminescent tube shown in Figure 1 partially brokenaway to more clearly disclose certain features of construction.

As conducive to a clearer understanding of certain features of myinvention it may be noted at this point that luminescent gaseousconduction devices or gas filled tubes of the class indicated varyonefrom another in the matter of electrical characteristics,particularly in the matter of electrical resistance, even where attemptis made in manufacture to produce identical tubes. Ordinarily thevarious tubes utilized in a single sign or display are of differentshapes and lengths, conforming to certain designs or configurations ,theapplied potential is ously affect the proportion of the so as to give adesired arrangement for a combined effect.-

It may be further noted that in the operation of luminescent gas filledtubes or devices of the character indicated from a source of alternatingcurrent electrical energy the instantaneous resistance of any one tubeor device varies greatly from the time when the instantaneous value ofinsufficient to causean ionized condition of the containedgas (duringwhich the tube is of high electrical resistance, is non-conductive andis non-luminous) and when the applied potential, in either thealternatively positive or negative portion of the cycle, has risen tosuch a value as to ionize the gas and thus cause the tube to become agood conductor of comparatively low resistance and luminescent. Wherethe ionized or conductive condition of the tube is established asubstantial current flows through the tube (tending to quickly increasedue to the decidedly negative resistance characteristics of such tubes)until the continuously changing applied potential has fallen to such alow value that the ionized condition of the tube may no longer bemaintained. At this timev the tube again becomes non-conductive andnon-luminous and remains so until the instantaneous value of the appliedpotential again rises, in following through the cycle of alterations, toapoint suflicient to again cause the gas to become ionized, conductiveand luminous. Y

The proportion of the time of a complete cycle of alternations of thesource of electrical energy that the gas filled tube is luminescentdepends first upon the proportionate length of time that the tube isrendered conductive (the proportionate period between the time when theinstantaneous potential becomes sufficient to ionize the gas containedin the tube and the time when this potential falls to such a value thatthe ionized condition may no longer be maintained) and second upon theproportion of this proportionate length of time that the current densitywithin the conductive tube (influenced by other elements, such.

as capacitances, inductances and resistances in 00 the electricalcircuit of the gas filled tube) is sufiicient to render the tubeluminescent.

The various gas filled tubes employed in a single display are ofdifferent electrical characteristics, particularly in the matter of theionizing potential, the potential at which ionization may not bemaintainedfand the electrical conductance (or resistance) during theionized condition. These characteristics, as indicated above, tend tovaritime any one of the tubes of the entire display is luminescent aswell as the degree or intensity of this luminescence.

Thus, one of the objects of my invention is to maintain the several gasfilled tubes or devices of a luminous sign system uniformly brilliantand luminescent for substantially the same length of time in spite ofinherently different electrical characteristics of the several tubes, asindicated above, as well as to increase the proportion of the time thatthe several gas filled tubes are rendered luminescent.

As more particularly indicated above, the resistance of any one of thegas filled tubes of a single system varies greatly from the unionizedcondition of the gas, during which the resistance is very high, to theionized and subsequent arc condition where the electrical resistance iscomparatively low and negative ineifect; characteristics which renderthe tube inherently unstable and exceedingly difiicult to effectivelycontrol.

In heretofore known systems and apparatuses of the class indicatedcumbersome and expensive choke-coil and/or resistances are included inseries with the various luminescent tubes in order to stabilize theoperation of these tubes and to limit the flow of current during theconductive period of the tubes to desired safe values.

Another object of my invention is to limit and control the flow ofcurrent in the various gas filled tubes of a single luminescent systemin a highly eificient and practical manner without sacrifice to theuniform brilliant operation of the tubes and the proportionate timeduration of the luminescence thereof.

. tem or excited from separate electrical transforming apparatusconnected with a single source of power. from a common source of highpotential electrical energy there is a great tendency, due to theinstability of tubes of the class indicated, for the tube of loweststarting potential or the tube of greatest conductivity when ionized, tobecome overloaded and to cause a non-uniform operation of the tubestaken as a group. All of these systerns and apparatuses are large andcumbersome requiring much expensive apparatus which is costly tomaintain and operate and which is generally inefficient and unreliable.

Accordingly, one of the outstanding objects of my invention is toprovide a system and apparatus of compact, inexpensive and practicalconstruction for operating luminescent tubes or gaseous conductiondevices of the class indicated in an economical and thoroughly reliablemanner from readily available alternating current electrical.Illustratively, the tubes or devices 10, 11, and 12 are ofapproximately the same size and voltage rating while the devices 13 and14 are of approx- Where a number of tubes are energized imately per centincreased size and voltage rating.

Each of the gaseous conduction devices (see Figure 2) is conveniently inthe form of an elongated clear glass envelope 10a with metallicelectrodes 10b and 10c mounted within the glall envelope andmechanically supported by sealed electrical terminals 10d and 10erespectively. A gas of such character and at such low pressure as tobecome luminescent upon proper electrical excitation, such as neonmaintained at a reduced pressure, is enclosed within the glass envelope10a.

As the column of gas within the envelope is excited by the applicationof a suitable electrical potential across the terminals of the tube, asdescribed more fully hereinafter, the gas is ionized, and renderedconductive, and becomes luminescent giving forth, for neon, a red-orangeglow. Where the proper potential is maintained across the terminals ofthe luminescent tube or gaseous conduction device, all as moreparticularly described below, the luminous glow of the gas istransmitted through the clear glass walls of the tube and gives auniform and brilliant glow along the length of tube.

Referring now back to Figure l, the various luminescent tubes 10, 11,12, 13 and 14 are preferably supplied with alternating currentelectrical energy from a readily available single phase source ofelectrical energy 15 illustratively 220 volts cycles, which is connectedto the tubes by an electrical system and apparatus more fully describedbelow. i

In accordance with the provisions of my invention electrical energy fromsource 15 is supplied the primary winding 16 of a single coretransformer generally denoted at 17 by means of suitable conductors 18and 19. A plurality of coil sections, preferably of an even number andof equal voltage and impedance ratings, illustratively four, 20, 2-1, 22and 23 comprise the high voltage secondary winding of the transformer.Conveniently the primary winding 16 and the secondary winding2021--22-23 are mounted on a single iron core diagrammatically indicatedat 24.

The various secondary coil sections, 20, 21, 22 and 23 are preferablyconnected in series by means of conductors 25, 26 and 27 so that theelectromotive forces induced in the several coil sections are additive.

In order that maximum secondary potential may be achieved with a minimumof expensive insulation, the amount and cost of which rapidly increaseswith the electrical potential for which the apparatus is to beinsulated, the mid-point of the secondary winding is preferably groundedas at 28. While maximum electrical potential is established betweenconductors 29 and 30 connected respectively to coil sections 20 and 23only one-half of this potential need be insulated against since butone-half of this maximum value exists between the high-potentialconductor 29 and ground 28 and between conductor 30 and theground.

In addition to the economies in construction indicated above and adecreased danger to life and property because of the high electricalpotentials employed, by grounding the seriallyconnected coil sections ata mid-point there is achieved a balanced transformer secondary systemthe advantages of which will appear more fully hereinafter.

The several gaseous conduction devices 10, 11 and 12 of equal ratingsare supplied with highpotential electrical energy from combinations 01',

,for example, two of the four transformer secondary winding coilsections; the combination of coil sections connected to any one of thegaseous conduction devices is not repeated but each conduction device issupplied with electrical energy from a combination of series connectedcoil sections which is not duplicated in any of p the others.

For example, luminescent tube or gaseous conduction device 10 issupplied with high-potential electrical energy from the transformersecondary I winding coil sections and 21 which, as indicated above, areconnected in series by a conductor 25, by way of the conductors 29 and26. Likewise, tube 11 is supplied with high-potential electrical energyfrom coil sections 21 and 22,, which are connected in series by aconductor 26, by way of conductors and 27. And tube 12 is similarlysupplied with energy from coil sections 22 and 23,

' serve a balanced condition in the secondary circuit of thetransformer.

The, illustratively, two gaseous conduction devices-of increased rating13 and 14 (about per 'cent greater resistance than tubes 10, 11 and 12)are so connected to the secondary winding of transformer 17 that a 50per cent increased electrical potential is applied thereto all withoutdisturbing the balance of the secondary circuit. Thus, referring toFigure 1, the tube 13 is supplied with high potential electrical energyfrom the secondary winding coil sections 20, 21 and 22 (seriallyconnected, as indicated above, by conductors 25 and 26 respectivelyinterconnecting sections 2021 and 2122) by way of conductors 29 and 27.Similarly, tube l4is connected to the serially connected "coil sections21, 22 and 23 (interconnected by conductor 26 for sections 21-22 andconductor 27 for sections 22 23) by way of the conductors 25 and 30.

'In the operation-of my electrical luminescent sign system andapparatus, as high-potential electrical energy is supplied the variousluminescent tubes, all as more particularly described above, these tubesbecome conductive, and hence luminescent, when the instantaneous valuesof the various applied potentials are sumcient to establish an ionizedcondition within the respective tubes. For a cycle supply of alternatingcurrent electrical energy the tubes are rendered alternatinglyconductive and non-conductive, and consequently luminescent andnon-luminescent, 120 times per 5 second (once for the positive half andonce for the negative half of each cycle). Due to the persistence ofvision the tubes appear to glow continuously.

As soon as the conductive condition is estab- J llshed'the resistancesof the various tubes (initially very high) drop to low values whichbecome efiectively negative. -In order to prevent the electric currentin the various tubes or gaseous conduction devices from rising toexcessive instantaneous values under these highly unstable conconductiondevices decrease to values which, while Where capactive impedanceelements are em- 'ployed in series with each of the several tubes thehigh inductance of the transformer secondary winding included in thecomplete energization circuit for any one tube is largely compensatedfor. The time required for the current to build p to a value sufilcientto cause a desired illumin tion of the tube is thus greatly reducedwhile the proportion of the time during which the tube is renderedconductive and a current of high density flows is brought to a maximum.This permits the tube to be luminescent a greater portion of each cycleof the impressed" potential, and the related flow of current, andthereby gives an increased brilliancy of operation.

Since each of the several gaseous conduction devices is supplied withhigh-potential electrical energy from diiferent portions of thetransformer secondary winding a desired current density in each tube isindependently achieved and a uniform brilliant operation of the varioustubes is assured in spite of slight inequalities in tube constructionand in the electrical characteristics thereof (starting potential,maintenance potential, initial un-ionized resistance, ionized resistanceand the like). Thus highly efilcient operation of a luminescent signsystem of the character indicated is achieved with a minimum of riods ofthese tubes, the current density of the tube or device 13, and hence thebrilliancy of the luminescent glow emitted, may be effectively I limitedby connecting the resistance element 36 in series with thehigh-potential circuit energizing the device.

Likewise, the difference in conductivity and luminosity of the otherdevices may be varied to achieve a uniform brilliancy of the entireluminous display.

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As more particularly indicated above the high inductive resistance ofthe several individual luminescent tube circuits is largely compensatedfor by the condensersconnected in series with the respective tubes. Inorder to obtain maximum operating efliciency of my electrical system Theuse of the additional condensers 37, 38, 39.

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and 40 as indicated above compensates for the excess inductive reactanceof the transformer secondarywinding coil sections and brings the powerfactor of the several parts of the secondary circuit to unity without,at the same time, undesirably affecting the balanced condition of thesystem and the current limiting function of the condensers connecteddirectly in series with the several luminescent tubes.

My system and apparatus for operating a number of luminescent tubes inaddition to assuring maximum uniform brilliant operation of the tubespermits a direct saving in cost of operation. The losses are minimizedand the power required of .1 the source of supply energy is reduced to aminimum value for uniform brilliant operation of the luminescentdisplay.

Thus it will be seen that there has been pro- ,vided in this invention asystem and apparatus in understood that an uneven number of sections maybe used where such a practice is found desirable, as where the secondaryload circuit is unbalanced. Likewise, while single luminescent gaseousdischarge devices or tubes are connected to various combinations oftransformer secondary winding coil sections it will be understood that aplurality of series-connected luminescent tubes of reduced rating mayreplace one or more of the individual tubes as desired.

As many possible embodiments may be made of my invention and as manychanges made in the embodiment hereinbefore set forth it will beunderstood that all matter described herein or shown in the accompanyingdrawing is to be interpreted as illustrative, and not in a limitingsense.

What is claimed is,

1. In 'a luminescent tube system having a plurality of luminescenttubes, in combination, a transformer having a secondary winding dividedinto a plurality of-series-connected coil sections arranged in equalnumbers at opposite sides of a zero potential point of said winding, anda plurality of parallel tube circuits connected to the secondary windingof said transformer so that each of said circuits is connected to aparticular grouping of the coil sections of said transformer secondarywinding that is not duplicated in any of the companion tube circuits.

2. In a luminescent tube system having a plurality of luminescent tubes,in combination, a transformer having a secondary winding divided into aplurality of series-connected coil sections arranged in equal numbers atopposite sides of a grounded neutral point of said winding, and aplurality of parallel tube circuits connected to said winding so thateach of said circuits is served by a particular grouping of the coilsections of said transformer secondary winding that is not duplicated inany of the companion tube circuits and so that the loads on oppositesides of the zero potential point of said secondary winding aresubstantially balanced.

3. In a system and apparatus of the character coil sections of saidwinding that is not duplicated in any of the companion circuits, wherebyeach of said circuits is operated at a voltage corresponding to thesumof the separate voltages of the coil sections included therein.

4. In a system and apparatus of the character described, in combination,a single phase single core transformer having a secondary windingdivided into a plurality of coil sections, a plurality of devices havingnegative resistance characteristics, and a plurality of parallelcircuits connected to said devices and to said secondary winding so thateach of said devices is connected to a particular grouping of the coilsections of said secondary winding that is not duplicated in any of thecompanion circuits and is operated at a voltage corresponding to the sumof the separate voltages of the coil sections included therein, theconnections between said secondary winding and said parallel circuitsbeing such that the number of coil sections included in certain of saidcircuits differs from that included in the remaining circuits.

5. In an electrical tube system, in combination, a source of alternatingcurrent electrical energy, a transformer having a primary winding and aplurality of secondary winding sections, a plurality of gaseousconduction devices, means for connecting the primary winding of saidtransformer to said source, and means for connecting said gaseousconduction devices to non-repetitive combinations of the plurality ofsecondary winding sections of said transformer.

6. In an electrical luminescent tube system, in combination, a source ofsingle phase alternating current electrical energy, a single phasetransformer having a primary winding and a plurality of secondarywinding coil sections, means connecting the primary winding of saidtransformer to said source, a plurality of luminescent tubes,

and means including impedance elements for connecting said tubes tonon-repetitive combinations of the secondary winding coil sections ofsaid transformer.

7. In an electrical tube system, in combination, a source of alternatingcurrent electrical energy, a transformer having a primary winding and aneven number of secondary winding coil sections, means connecting theprimary winding of said transformer to said source, a plurality ofluminescent tubes, means connecting the secondary winding coil sectionsof said transformer in series forming a balanced secondary circuitgroundedat mid-point, and means connecting said luminescent tubes tosaid last-mentioned means in non-repetitive combinations and maintainingthe balance of said secondary circuit.

8. In an electrical tube system, in combination, a transformer having aprimary winding and a secondary winding comprising a plurality of coilsections, a plurality of luminescent gaseous conduction devices, meansconnecting said gaseous conduction devices and said coil sections sothat each of said devices is connected to a series connected combinationof said coil sections that is not duplicated by the others of saiddevices, and capacitive means connected in parallel with the coilsections of said transformer secondary to said source, means includingimpedance elements for connecting said gaseous conduction.

devices to non-repetitive combinations .of the plurality of secondarywinding sections of said transformer, and capacitive means connected inparallel with said secondary winding sections for improving theoperation of said gaseous conduction devices.

CHARLES PHILIPPE BOUCHER.

